The present invention relates to a tappet or a valve lifter for use in a reciprocating internal combustion engine.
In a known tappet for an internal combustion engine, for example, carburizing hardening has been applied to a tappet body made of steel or cast iron. Recently, coated light alloys have been used in Japanese Utility Model Laid-Open Pub. No. 63-174508; NiP alloy plated metal in Japanese Utility Model Laid-Open Pub. No. 62-138803; and Fe-C sprayed metal in Japanese Patent Laid-Open Pub. No. 1-315607.
However, in the known steel or cast-iron tappets or light alloy tappets which are subject to surface treatment, there are disadvantages such as increase in mass in steel or cast iron tappets; increase in cost in tappets as disclosed in Japanese Utility Model Laid-Open Pub. Nos. 63-174508 and 62-138803; and decrease in toughness of a sprayed layer as disclosed in Japanese Patent Laid-Open Pub. No. 1-315607, which could not be solved sufficiently.
In view of the disadvantages, the object of the present invention is to provide a light-alloy tappet in an internal combustion engine having low cost, a wear-resistant sprayed layer and high toughness.